The present invention relates to a sintered ceramic article and a method of manufacturing the same, and more particularly to a sintered ceramic article in the form of a composite body made of ceramic and metal and having high toughness and mechanical strength and a method of manufacturing such a sintered ceramic article.
Ceramics are widely used recently to manufacture various mechanical components since they are excellent in mechanical strength and heat resistance. It is known, however, that ceramics are generally poor in toughness. There have been proposed sintered composite ceramic materials made of ceramic and metal in order to eliminate the problem of poor toughness.
According to one known process of producing such a sintered ceramic material, ceramic powder and metal powder are mixed together and formed into a certain shape, and the shaped article is fired by being heated at a high temperature to produce a sintered product. With the conventional process, however, since the firing temperature is higher than the melting point of the metal powder, the metal powder is melted in the firing step and the metal particles are coagulated or not uniformly dispersed in the sintered product. As a result, the produced sintered ceramic article tends to have different local mechanical strengths or toughnesses.
There has been proposed a method of producing a sintered ceramic article by forming a shaped article made of a mixture of ceramic power and metal carbide or metal nitride, and burning the shaped article in a reducing atmosphere to separate out the metal. One problem with this process is that a relatively large amount of metal is separated out in the surface layer of the sintered ceramic article, whereas a less amount of metal is separated out within the sintered ceramic article. Accordingly, it is difficult to uniformly metallize the sintered article in its entirety, and the sintered article cannot have a desired degree of toughness.